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Physio: Respiratory > Pulm. Function Tests > Flashcards

Pulm. Function Tests Flashcards

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1
Q

Pulmonary function tests include:

A
  • CXR
  • ABG
  • Spirometry with FEV 1
  • FVC
  • FEV1/FVC
  • FEV 25-75
  • flow volume loops
  • V/Q scan
  • pulse ox
  • SaO2 from ABG
  • mixed venous O2
  • sat from Pa cath
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2
Q

What should mixed venous sat be?

A

75%

If lower—> increased O2 consumption or not getting enough O2

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3
Q

What are indications for PFTs?

A
  • possible pneumectomy or lobectomy
  • surgery of upper abdomen
  • hx of pulm dz
  • severe obesity
  • OSA
  • pickwickian syndrome
  • evidence of pulm. Dysfunction during physical exam (DOA) ** dyspnea at rest is a sign of bad pulm dysfunction
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4
Q

What is pickwickian syndrome?

A

Combo of conditions:

  • obesity
  • decreased pulm. Function
  • polycythemia
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5
Q

What PFT values indicate high risk?

A
  • FEV1 < 2L
  • FEV1/FVC < 0.5
  • VC <15ml/kg (adult) 10 mL/kg (child)
  • VC <40-50% than predicted (usually 80%)
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6
Q

What does obtaining PFTs preoperatively help with?

A

Estimates pulmonary reserve to better plan pre, intra, and post op. Pulm care requirements

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7
Q

How do you optimize a pt preoperatively?

A
  • bronchodilators *most important** >15% improvement in FEV1 after 1 tx
  • CHF: (with rales)diuretics the night before
  • antibiotics: sputum c and s
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8
Q

How do you optimize a pt intraoperatively?

A
  • emphysema requires longer “E” time on vent
  • closely monitor PIP—> emphysematic blebs can rupture
  • CO2 retainers: keep CO2 near baseline (may be 50-60)
    • rapid correction leads to met. Alkalosis
    • CO2 retainers have high HCO3 too
  • Bronchospasm: avoid histamine releasing drugs (morphine)
    • tx. With nebulized albuterol
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9
Q

What’s the best way to give neb. Albuterol intraop.?

A

Vent. Inline T piece—> use O2 10L/min to run

- give proposal to make up for diluted agent

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10
Q

How do you optimize a pt post-operatively?

A

Make sure they meet proper extubation criteria:

  • VSS, awake and alert, RR <30
  • ABG on Fio2 40%:
    • PaO2 >70
    • PaCO2 <55
  • MIF (Max inspiratory force) more negative than -20cmH2O
  • VC >15mL/kg
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11
Q

How do you obtain MIF?

A

Obstruct airway during inhale, see how negative a force they can generate

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12
Q

What are the different FEV1 ranges and their predictions during extubation?

A
  • FEV1 >50%—> extubation probably not effected
  • FEV1 25-50%—> some hypoxemia and hypercarbia
    • prolonged intubation probable
  • FEV1 <25%—> only life saving procedures should be done
    • regional anesthesia if possible
    • long term vent support
    • inability to wean possible
      • Trach. Probable
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13
Q

What are the criteria for acute resp failure?

A
    • KNOW WHEN TO INTUBATE ** (no one every got sued for putting in a tube)
  • mechanics: RR > 35, VC <15mL/kg, MIF more negative that -20mmHg
  • oxygenation: PaO2 <70 on Fio2 40%
    • A-a gradient >350 mmHg on 100% O2
  • ventilation: PaCO2 >55% (except when chronic).
    • Vd/Vt >0.6 (normal dead space is 30%)
  • clinical: airway burn (intubate sooner, before edema), chemical burn, epiglottitis, Mental status changes, fatigue, rapidly deteriorating pulm status
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14
Q

What will a CXR show with pleural effusions?

A

Blunted costophrenic angles

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15
Q

Why get an expiratory CXR?

A

Heart looks wider
Best to view pneumothorax
- less air (black on x-ray) in lungs so more can be seen

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16
Q

What do you do if pneumothorax is seen on CXR?

A

Consult thoracic surgeon for chest tube

  • give 100% FiO2
  • s/s include JVD, tachycardia, hypotension
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17
Q

What do you do if a tension pneumo is seen on CXR and how can you tell?

Study These Flashcards
A

right heart border is gone: lung tension is pushing on it

  • treat immediately! —> needle decompress
    • mid claviclular line
    • then get chest tube
18
Q

What does CHF look like on CXR?

19
Q

What does RUL consolidation signify on a CXR?

Study These Flashcards
A

Aspiration PNA

  • wont’ see it right away
  • after aspiration, get baseline CXR anyway
20
Q

How long do you have to run an ABG?

Study These Flashcards
A

15 min—> or glycolysis will occur, with lactic acid production, decreased pH and increased CO2
- can be stored on ice for 1-2 hours

21
Q

Which pressure correlates best with arterial pressure?

Study These Flashcards
A

Brachial pressure coming off pump

22
Q

What are ABG norms?

Study These Flashcards
A
  • pH: 7.35-7.45
  • PCO2: 35-45 mmHg
  • PO2: 75-105 mmHg
  • HCO3: 20-26 mmoles/L
  • BE: -3 to +3 (0)
23
Q

What are some buffers in the blood?

Study These Flashcards
A

Substances that can absorb or donate H+

  • HCO3
  • Hg
  • serum proteins
  • phosphate (HPO4)
24
Q

What is true regarding CO2 and pH?

Study These Flashcards
A

An increase of PCO2 by 10mmHg causes a decrease in pH by 0.08

25
Can the body buffer acidosis or alkalosis better?
Acidosis
26
What is the difference between hypoxemia and hypoxia?
Hypoxemia: decreased O2 in blood, < 70 Hypoxia: a low O2 state
27
How do you calculate PaO2?
(Pb - PH2O) x (FiO2) - (PaCO2/0.8) Pb= 760 PH2O= 47 Normal PaO2 on room air (.21)= 100
28
What is a normal A-a gradient?
~ age/3 Widens during anesthesia with intrinsic lung dz (Pneumo, shunt. V/Q mismatch)
29
Is the A-a gradient normal in hypoventilation or low FiO2?
Yes, just treat with supplemental O2 | - adjust vent and PEEP, treat underlying cause
30
How does bicarbonate affect pH?
A decrease in HCO3 by 10 mmoles, decreases the pH by 0.15 | And vice versa
31
Total bicarbonate deficit=
Base deficit x wt in kg x 0.4 —> usually replace 1/2 of deficit in mEq/L (Good equation to use in trauma pt)
32
What causes respiratory acidosis?
``` Low pH, high CO2 * hypoventilation and hypercarbia - CNS depression - trauma - drugs - obesity - decreased FRC - airway obstruction - COPD, asthma, pulm fibrosis * after 1-2 days kidneys reabsorb HCO3 —-> partially corrects, not completely ```
33
What causes respiratory alkalosis?
``` High pH, lowCO2 *hyperventilation with hypocarbia - hypoxic respiration - CNS disease/encephalitis - anxiety - narcotic W/D - PREGNANCY - early septic shock - hypermetabolic states - artificial ventilation —> kidneys compensate by excreting HCO3 and H+ - both partially correct alkalosis ```
34
What are causes for metabolic alkalosis?
High pH, high HCO3 - bicarbonate infusion - metabolism of lactate or citrate - loss of H+ from vomiting or NGT auctioning —>resp compensation limited—> hypoventilation - can only hypoventilate so much - kidneys may increase HCO3 secretion
35
What causes metabolic acidosis?
Low pH, low HCO3 - lactic acidosis from hypoperfusion, DKA, renal dz with HCO3 loss, diarrhea (especially in kids), ASA ingestion, high protein intake —> resp compensation- with hypercarbia (central chemoreceptors) -hyperventilation - resp faster than kidneys—> increase H+ excretion
36
What is FEV1?
* the most important clinical tool in assessing severity of obstructive disease * FEV1= after max inspiration, the volume of air that can be forcefully expelled in 1 second - normally 3-5L -can be reported as % of FVC - FEV1/FVC—> normallly >75%
37
What degree of obstruction lung dz risk do these values of FEV1/FVC represent? >75, 60-75, 45-60, 35-45, <35
``` >75—-> normal 60-75—> mild Lung dz 45-60—> moderate lung dz 35-45—> severe lung dz <35—-> extreme lung dz ```
38
What do flow volume loops do?
Help distinguish upper airway from lower/generalized pulm dz - Extrathoracic (upper airway obstruction)= decreased insp. Flow - intrathoracic (lower airway obstruction)= decreased expiratory flow
39
What does FEV 25-75 measure?
Forced expiratory flow at 25-75% of FVC - effort independent - sensitive indication of early airway obstruction - reflects collapse of small airways and peripheral airways
40
What is the MVV or MBC test?
The will to live test - max amount of air pt can exhale in 1 minute at maximum effort (hyperventilation) - tests motivation, mechanics, strength, endurance * a decrease predicts increased morbidity and mortality in pts undergoing thoracic surgery
41
What do MVV and MBC stand for?
MVV: max voluntary ventilation MBC: max breathing capacity

Physio: Respiratory (5 decks)

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